1. Field of the Invention
The present invention is directed to a detector for the image brightness on the output screen of an x-ray image intensifier, and in particular to such a detector formed by a matrix of detector elements.
2. Description of the Prior Art
Detectors which are formed by a matrix of individual detector elements are known in the art and are used to detect the image brightness which is present at the output screen of an x-ray image intensifier in x-ray diagnostic systems. A detector of this type permits the detector elements to be selected in groups so that a desired measurement field, which can be used to acquire the actual value of the radiation dose rate, is formed. Compared to the use of a photomultiplier as a detector for this purpose, a significantly larger number of different measurement fields are available for selection in a matrix-type detector. Selection of different sizes and shapes of measurement fields is desirable, for example, to match the size and shape of a measurement field to the particular organ under examination for medical diagnostic purposes.
In a known matrix-type detector as disclosed in U.S. Pat. No. 5,029,338, the detector elements are all of the same size and shape, i.e., they are all identically fashioned. Because of the identical fashioning of all of the individual detector elements, not all measurement fields which may be desired in practice can not be selected with this known detector.